This one's new to me... Your thoughts please gentlemen.

24EMan · May 18, 2022

So how about this metering setup anyone? I have never come across this setup before, and I wonder whether the client would be better off keeping it rather than persisting with his attempts to get a smart meter fitted because he's keen to monitor and reduce his bills.... that is I wonder how accurate this indirect metering actually is. I am going to suggest to him he does a simple test by running a known load and for a period and seeing what the meter records. He's had 4 appointments for a replacement meter cancelled in the past two years without anyone ever coming to visit, citing that his installation is not suitable for a smart meter.
Note the TNC earth arrangment, the exposed single insulation on the boot termination of the concentric lead in. The question I'm wondering is how the off peak metering could possibly be distinquested between the two separate tails that go through what I assume is a toroid. Surely this setup means all power consumption is metered either on the Low or Normal meter. The meter tails are have no fuse switch and the boards are over 8 metres away inside the building. I think I'll pass on any idea of removing the cutout fuse to work on this one.

Was this some DNO engineers experiment or was this a regular setup at some period in the distant past? Would be very interested to hear from the forum to share some information and knowledge about this setup.

Surprising what you find in these old farms and buildings in rural Cornwall.

[ElectriciansForums.net] This one's new to me... Your thoughts please gentlemen.

i=p/u · May 18, 2022

off peak timeslots= cheaper at these times

Dustydazzler · May 19, 2022

My hearts sings when I see RYB SWA

snowhead · May 19, 2022

The metering is 100% acurate for both normal and off peak as you'd expect from a DNO installation.
There's no issue with the Current Transformer.
And yet again a failure of the "Smart" people to understand what's there and be able to provide a solution.

That's an Economy 7 meter setup, where all the off peak use is at Low rate.
The time switch changes the meter over from Normal to Low (Off Peak), the arrow to the left of the totals will move from pointing at Normal to pointing at Low.

The timeswitch will switch a contactor for the Off Peak C.U that's at the other end of the SWA on the red and blue cores.
The contactor is normally at the meter location or the time switch is used to switch the Off peak load directly.
The control circuit including to the remote contactor is unmetered and is fused via the slidelock.

Lucien Nunes · May 19, 2022

Exactly. This is normal practice for a 200A supply and all metering of large supplies is done via current transformers.

24EMan · May 19, 2022

Dustydazzler said:
My hearts sings when I see RYB SWA

I have no idea where that SWA goes to and why it is connected to the time switch

24EMan · May 19, 2022

24EMan said:
I have no idea where that SWA goes to and why it is connected to the time switch

Sorry Snowhead.. missed the more detailed reply before that comment. Still have no idea where that contactor is. I can't see it near the Off Peak board.

24EMan · May 19, 2022

Lucien Nunes said:
Exactly. This is normal practice for a 200A supply and all metering of large supplies is done via current transformers.

Given the size of the tails would it be reasonable to assume this is still a 100A supply despite this metering arrangement? or does this arrangement mean there'll be a 200A cutout fuse (still can't fathom why these things were and are never marked up and properly identified)

snowhead · May 19, 2022

24EMan said:
(still can't fathom why these things were and are never marked up and properly identified)

When these set ups were installed they were done by and owned by the DNO.
All DNO meter men would know exactly what was what, wouldn't have needed lables and no-one then would have predicted deregulation followed by "Smart Metering".

Is the contactor inside the C.U?
The SWA is dropping out the bottom of the box, does it go underground around the property and back in?

R-fur · May 19, 2022

I sometimes came across large centraly fitted storage heating units that had ducts into each room. The heater elements were connected to the domestic supply and the off peak signal (the swa from the timeswitch) was an input to the control board to tell it that the house was now in low rate. The units I delt with were called Airdun units.

freddo · May 23, 2022

R-fur said:
The heater elements were connected to the domestic supply and the off peak signal (the swa from the timeswitch) was an input to the control board to tell it that the house was now in low rate

I trapped a wire in the metal cover on one of those once as I was trying to re fit it. It left a rather large blast mark on the kitchen floor...

pc1966 · May 23, 2022

The thickness of those wires troubles me, I am guessing/hoping that the thing between meter and time-switch is a fuse?

I presume the SWA to the time-switch is then going to some contactor for controlling the heating/off-peak loads?

pc1966 · May 23, 2022

Lucien Nunes said:
Exactly. This is normal practice for a 200A supply and all metering of large supplies is done via current transformers.

The concentric cable feeding it looks a bit thin for 200A?

Lucien Nunes · May 23, 2022

, I am guessing/hoping that the thing between meter and time-switch is a fuse?

Yes it is.

The concentric cable feeding it looks a bit thin for 200A

I find all concentric looks too thin.

freddo · May 23, 2022

Lucien Nunes said:
I find all concentric looks too thin.

We wired a load of properties, the DNO installed all 10mm2 concentric, 80A fuses in all the cutouts. Seems fine. I've measured 120A through 16mm sheathed singles on a looped supply. Also seemed fine, won't get any snow settling on the cables though...